1. Field of the Invention
The present invention relates to an alpine ski boot having at least one rear portion of the upper that is retractable towards the rear for introducing and/or extracting the foot of the skier and relates to the implementation of the flexion control means of the upper arranged at the rear of such a boot in the zone of the rear portion of the upper.
2. Description of Background and Relevant Information
This type of boot usually comprises a shell base surmounted by an upper at least partially journalled on the latter, for example, about a transverse axis, the upper comprising at least one front portion and one rear portion adapted to be separated from one another in the open position for passage of the foot. In these boots, at least one tightening system at least partially encircles the front and rear portions of the upper and is associated to at least one of the portions for maintaining these latter portions against the lower part of the leg of the skier in the skiing position.
Insofar as the flexion control means of the upper are concerned, various embodiments have been suggested. Most often, these means are constituted by springs or other elastically deformable elements positioned between the shell base and the rear portion of the upper that they connect to each other. These means generally project on a large zone of the rear portion of the upper and necessitate the implementation of numerous linking elements such as anchoring elements in the shell base and the upper, and guide and position maintenance elements for the springs adapted to intervene especially during flexion movements of the upper.
As examples, ski boots are illustrated in U.S. Pat. No. 3,619,914 and Swiss Patent Nos. 491,619 and 512,204, where such flexion control means are disclosed. As is clear from these documents, these flexion control means are complex and basically adapted for ski boots of the "top entry" type, due to the fact that they form a connection bridge between the lower shell and the rear part of the upper. Indeed, only this type of top entry alpine ski boot, that is provided with at least one upper opening-located on the front portion of the upper and/or the shell base, enables introduction of the foot in the boot without necessitating the disengagement or removal of the rear portion of the upper towards the rear.
Further, ski boots disclosed in the French Patent Publication Nos. 2,305,948 and 2,330,345 include flexion control means that are relatively flexible reinforcements, whose volume is almost entirely integrated to the rear portion of the upper. Such an embodiment of the means enables the construction of boots that are comparatively lacking in raised portions and/or projections on the outside of the shell, in comparison with those cited previously, and this especially enables a more rational use of the boots with ski clothes that normally cover the top of the upper of the boots. It remains, however, that such means cannot always be adapted to ski boots of the rear entry and/or the mixed entry type.
Indeed, to retain the boot structure for rear entry alpine ski boots, provided with a flexion control device of the upper which does not project on the rear portion of the upper, the most common solution has been to shift the elastic means from the rear portion of the upper to the front portion of this upper. A great number of boots have been manufactured according to such a structure, and we can cite for example, the boots taught in the French Patent Publication No. 2,096,248 and U.S. Pat. No. 4,095,356.
In French Patent Publication No. 2,096,248, the rear entry boot has a rear portion of the upper that is journalled on an axis of the shell base, and that achieves a blocking of the opening between the upper and the shell base at the level of the heel. A flap stirrup attached on one or the other of these elements fulfills the role of a closure element limited to the heel zone. In such a device, the control and limitation of flexion of the upper are only obtained by the elastic means arranged at the front of the boot, between the front portion of the upper and a front upper portion of the shell base.
U.S. Pat. No. 4,095,356 also discloses a rear entry type of ski boot, in which the front portion of the upper is journalled about a first axis corresponding substantially to the malleoli, the front portion comprising an extension towards the base bearing a second axis on which the rear portion of the upper is capable of pivoting with respect to the front portion. In flexion, the front spoiler rear spoiler assembly pivots about the first axis.
In the same way as described previously, the journalled flap represented closes shuts an opening limited between the rear portion of the upper and the shell base, but does not play any role in the flexion control of the upper, which role is fulfilled by a joint positioned between the lower front edge of the front portion of the upper and the upper front edge of the shell base.
It is clear that the boots mentioned above in French Patent Publication No. 2,096,248 and U.S. Pat. No. 4,095,356 enable an easy entry into the boot from the rear due to the fact that the flexion control means have been shifted to the front of the upper. However, this arrangement of the control means at the front has some disadvantages when used, because the resisting forces of the means are localized on the front surface of the lower part of the leg of the skier, that is, contacting the bony portions of the latter which are the least protected. The result is that these bony portions are sensitized to a lesser or greater degree, and this results in irritation, even the formation of callouses, which, at the very least, adversely affect the comfort of the skier.
It is especially for this reason that it was estimated that a retention of the upper at the rear, by means of an upper assembly forming a collar, would have the effect of distributing the forces along the entire perimeter of the lower part of the leg, without any localized support or force.